Disk drives for removable magnetic and optical disks have been available for some time. Magnetic disks generally come in a flexible form known as floppies, or a relatively rigid form known as hard disks, whereas optical disks are embodied in relatively rigid media. Typical flexible disk drives and cartridges are shown in U.S. Pat. Nos. 4,445,155 to Takahashi, et al.; 4,445,174 to Takahashi; 4,546,397 to Asami, et al; 4,573,093 to Obama, et al; and 4,675,758 to Tanaka. Typical removable hard disk drives and the cartridges therefor are shown in U.S. Pat. Nos. 4,488,187 to Alaimo; 4,503,474 to Nigam; 4,504,879 to Toldi, et al.; 4,683,506 to Toldi, et al.; 4,717,981 to Nigam, et al; 4,722,012 to Toldi, et al.; 4,864,452 to Thompson, et al.; 4,870,518 to Thompson, et al.; 4,864,437 to Couse, et al.; 4,920,462 to Couse, et al.; 4,965,685 to Thompson, et al.; and 4,965,691 to Iftikar, et al. Disk drives having removable disks usually have some sort of entry door and a mechanism to receive a disk cartridge when it is inserted into the drive to assure proper connection therebetween. Most of such disk drives include a motor or solenoid which, after actuation by partial manual insertion of the disk cartridge, draws the cartridge into the drive, moves a shutter to open a window for access to the disk and positions read/write heads on one or both sides of the disk for data reading and writing. When a floppy disk or an optical disk is involved, usually the heads are driven linearly, such as by a stepper motor or linear voice coil actuator, whereas when a hard disk is involved, a linear actuator may be used or the heads may be moved arcuately across the disk by a rotary voice coil actuator. In floppy disk drives, the heads are designed to lightly touch the magnetic media during reading and writing. In optical drives, the read/write heads are spaced a safe distance away from the disk, laser beams being used in most instances to read and write the optical information. In magnetic hard disks, the read/write heads float on an extremely thin layer of air so they never touch the disk while the disk is spinning. Unlike floppy disks which wear out after a short use time, this allows hard disks to last the lifetime of the computer to which they are connected. Dust or other contamination, if it is the correct size, can get between the read/write heads and the disk and cause damage to the magnetic media of a hard disk. For that reason, nonremovable hard disk drives are sealed. In removable cartridge hard disk drives, means must be provided to minimize contamination, especially in the size of 0.1 to 4 microns, because particles smaller than that pass between the disk and a head in the layer of air and particles larger than that tend to be knocked out of the way by the head.
Generally, the requirements for a hard disk cartridge are: protect the disk from damage and contamination; provide access for the read/write heads on both sides of the contained disk; provide a positive rotational interface to the disk drive for spinning the disk; provide sufficient rigidity to assure that all but extreme stresses do not cause the cartridge housing to bend and come in contact with the disk; provide some sort of mechanism to open the contamination preventing shutter of the cartridge when the cartridge is inserted into the disk drive and to close the shutter as the cartridge is being ejected; and do all of this in a minimum volume. Heretofore, most removable hard disks have been available in a cartridge about 6" square and over 1/2 "thick. The disk drive must accommodate the cartridge internally for contamination control. Therefore, removable cartridge disk drives must be proportionately larger than those with nonremovable disks, since removable cartridge disk drives have been too big to serve as internal disk drives in lap top or notebook size computers. Also, prior art removable cartridge disk drives, with their ejection system motors and disk retaining solenoids, use a relatively large amount of power when compared to small, efficient, sealed hard drives.
Therefore, there has been a need to provide a hard drive with very low power requirements, which uses removable cartridges having minimal size so that it can physically fit in available space in lap top and notebook sized personal computers and not reduce the battery powered operating life thereof, while being lightweight, fast, reliable, economical to manufacture, rugged and capable of storing large amounts of data.